[blvr]

For those that aren't aware, there's tools to help with this.

    f.lux    | Windows, OS X, iOS (jailbreak needed) | http://stereopsis.com/flux/
    Redshift | Linux, Windows (experimental)         | http://jonls.dk/redshift/
    Lux      | Android                               | https://play.google.com/store/apps/details?id=com.vito.lux

Lux isn't as nice as the others because it doesn't change colour temperature, it just puts a red/brown overlay over the screen. AFAIK there's no way to change the screen's colour temperature in Android.

[polshaw]

I was literally looking for flux on linux just before coming to HN to read this, so i can tell you flux is available for linux[1], although there can be issues; which prompted the creation of redshift.

1. see http://stereopsis.com/flux/linux.html

[chrishenn]

I used xflux when I used linux a while back, it worked very well.

[bhousel]

For Android, I use the Chainfire 3D driver + CF.lumen plugin. You need to have root though.

[duck]

I had no idea about any of these, thanks for sharing!